Manually operable balanced doors are known and have been used fairly extensively in modern buildings. In a typical construction, the balanced door is mounted in a doorway comprised of an upper header, a pair of side jambs, and the base. A hinge shaft is disposed in one side of the door frame, from which extend upper and lower door pivot arms. A guide track is mounted in the underside of the header, and a cylindrical guide roller is mounted on the top of the door. The door then rides on the pivot arms, with the cylindrical guide roller guided within the guide track. A door closer is usually disposed within the frame header to control the rotation of the door. The door closer will prevent the door from being opened too far so as to prevent damage to the guide roller or the door itself, and is also intended to provide additional force to close the door, but without having the door bang closed.
In one prior version, a linkage mechanism is disclosed within the header to couple the check shaft of the door closer to the hinge end of the upper door pivot arm so that the closer applies a rotational force to the upper pivot arm. This is disclosed in U.S. Pat. No. 3,605,339 which issued Sep. 20, 1971 to Catlett et al. However, this prior arrangement has been unsatisfactory because the linkage does not provide enough control to allow the door closer to adequately work over an extended range of opening and closing. In addition, the linkage is unreliable and prone to breakage
In U.S. Pat. No. 4,286,411 a different configuration is proposed, in which an additional door closer arm (an example of which is shown as 18 in the FIG. 1) is used. However, the door closer arm is again subject to failure and additionally represents an extra arm extending outwardly from the header to the door. Such a door closer arm is unsightly and disturbs the clean lines of the door. Further, this door closer arm does not provide sufficient rotation of the check shaft of the door closer to provide as much control as may be desired, because due to geometry, the door closer arm only moves through a limited arc of about 130.degree..